Abstract

In the post-genomic era, the development of ‘Omic’ based approaches such as transcriptomic, proteomic, metabolomic, interactomic, and phenomic in several model organisms have paved the basis of “Functional Genomics”. This area of science deals with the understanding of large network of genes/proteins and integration of transcript data to proteins, and protein to metabolite, and the complex and dynamic interaction to develop a response or phenotype.

Abiotic stresses such as drought, high salinity, cold and heat adversely affect the plant growth and productivity. To combat various environmental cues, as an adaptive mechanism, various signaling cascades get activated in the plant cell leading to altered cellular function and responses. Reversible protein phosphorylation mediated by kinases and protein phosphatases is one such adaptive cellular response to maintain a critical balance in phospho-regulation during normal and adverse growth conditions. A genome wide identification of protein phosphatase encoding genes in rice showed the presence of 132 genes (OsPPs). Protein structure, domain and sequence analysis divided entire protein phosphatase complement into PP2A, PP2C, PTP, DSP and LMWP classes and PP2C forms a major group with 90 members in rice genome. Phylogenetic analysis revealed that protein phosphatase family is highly conserved in different plants species. Detail expression profiling revealed a large proportion of protein phosphatase genes express differentially under abiotic stresses and during developmental stages and suggested their potential involvement in signaling networks triggered by abiotic stresses and developmental events. 

To examine the functional role in-planta, a potential protein phosphatase candidate OsPP108 was selected based on its differential expression profile under abiotic stresses (especially, drought and salt). OsPP108 is one of the group A PP2C from rice which, like other PP2C members of this group from rice and Arabidopsis negatively regulate ABA signaling and OsPP108 overexpression results in high ABA insensitivity at the seed germination and early seedling development. Detail molecular investigation identified OsPP108 as a novel regulator of stress signaling, where it negatively regulate ABA signaling but acts as positive regulator of abiotic stress signaling in plants. In future, transgenic rice plants overexpressing this gene might provide an answer to the problem of low crop yield and productivity during adverse environmental conditions.